The present invention concerns a method for producing portable objects with a card format and in particular objects comprising firstly a plastic object body composed of plastic sheets covered by external covering sheets or overlays, and secondly an antenna whose two terminals are connected to the connection pads of an integrated circuit chip embedded in the card body.
These portable objects with a card format are suitable for functioning with electric contact with the aid of an inductive coupling between the antenna of the card body and that of an associated reader. They are used in particular as a badge or transport right for access to protected premises.
So as to produce these objects, the method is carried out conventionally as shown on the accompanying FIGS. 1 and 2.
First of all, polycarbonate sheets (PC) are offset-printed in four colours. The front of a first sheet 1 of PC is printed and the back of a second sheet 2 is printed.
In addition, a predetermined number of chips 3, previously provided with protuberances 4, is mounted on a PVC support sheet 5 and so as to electrically connect the connection pads of each of said chips 3 to the terminals of an antenna 6 serigraphed on the surface of the support sheet 5. A sealing resin 7 is then deposited at the location of the connections and on the active face of the chip 3.
Then, after having serigraphed a thermoactivable glue on each sheet, the following are superimposed in the following order: a first external coating sheet 8, the second sheet 2 of PC, the support sheet 5 bearing the chip 3 and the antenna 6, a sheet 9 for incorporating this chip 3, the first sheet 1 of PC and a second external coating sheet 10. The sheets 5, 9, 8 and 10 are PVC sheets. This results in obtaining a superimposed unit with the thicknesses of the various sheets being the following:
first external coating sheet: 50 xcexcm
first PC sheet: 150 xcexcm
incorporation sheet: 300 xcexcm
support sheet: 190 xcexcm
chip: 260 xcexcm
second PC sheet: 150 xcexcm
second external coating sheet: 50 xcexcm
This unit is then subjected to a first and then second hot rolling according to defined temperature and pressure cycles. In particular, the first rolling, carried out at a temperature of about 140xc2x0 C., is intended to glue the sheets making up the unit via activation of the thermoactivable glue and to ensure that the chips 3 are incorporated in the incorporation sheet 9, and the second rolling carried out similarly at a temperature of about 140xc2x0 C., is intended to improve firstly adherence between the various sheets of the unit, and secondly the surface condition of said unit.
Then the rolled unit is cut and finally portable objects with a card format are obtained as defined in the standard ISO 7816-1, that is with a thickness of about 0.760 mm, a length 85 mm and a width of about 54 mm.
However, the method described above has certain drawbacks.
It requires the presence of two main thermoplastic materials: PC and PVC. Now, the vitreous transition temperature of the PC, which is about 150xc2x0 C., is higher than the vitreous transition temperature of PVC which is only about 70xc2x0 C. Thus, the PC does not reach its vitreous transition temperature during the first and second rollings. This is why it is necessary to glue the various sheets together using a glue.
Moreover, control of the offset printing of the PC is imperfect, as with the cutting of this plastic material, originating from imperfections of cards.
Of course, so as to mitigate the drawbacks of the method described above, it has been considered replacing the PC sheets by PVC sheets. However, the cards then obtained would have exhibited on their surface and on the vertical line above and below the chip appearance defects consisting of the presence of white traces due at these locations to a polymerisation/depolymerisation of the PVC of the various sheets of the rolled unit and in particular of the covering sheets in specific conditions differing from conditions existing in the rest of the card body.
Also having regard to the above, a problem which the invention seeks to resolve consists of embodying a method for producing a portable object with a card format comprising:
an object body comprising a plastic support sheet, a plastic incorporation sheet, as well as a first and a second external covering sheet;
an antenna provided with two antenna terminals, and
an integrated circuit chip provided with two connection pads, said chip being incorporated in the incorporation sheet, each of said connection pads being electrically connected to one antenna terminal,
said method comprising a next stage according to which:
the chip is mounted on the support sheet,
a method which mitigates the above drawbacks and in particular makes it possible to avoid using PC but without the cards obtained having appearance defects.
In the light of this problem, the solution of the invention consists of providing a method of said type characterised in that it comprises the following stages according to which:
the support sheet is rolled on which the chip is mounted with the incorporation sheet so as to obtain a first rolled unit in which the chip is incorporated in the incorporation sheet, and in a subsequent stage,
the first rolled unit is covered with the first and second recovering sheets.
Thus, by proceeding in two stages with the obtaining of a first PVC rolled unit and then by covering this first unit with covering sheets, it is possible to use solely a given plastic for the production of the sheets of the portable object in a card format and in particular to avoid using PC but without the card having appearance defects.
The following non-restrictive description clearly shows how the invention can be used in practice with reference to the accompanying drawings on which: